Normal pressure hydrocephalus

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Normal pressure hydrocephalus
Classification and external resources
ICD-10G91.2
ICD-9331.9, 331.5
DiseasesDB9089
MedlinePlus000752
eMedicineneuro/277 radio/479
MeSHD006850
 
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Normal pressure hydrocephalus
Classification and external resources
ICD-10G91.2
ICD-9331.9, 331.5
DiseasesDB9089
MedlinePlus000752
eMedicineneuro/277 radio/479
MeSHD006850

Normal pressure hydrocephalus (NPH), also termed symptomatic hydrocephalus, is a type of brain malfunction caused by excessive production of cerebrospinal fluid (CSF). Its typical symptoms are gait disturbance, urinary incontinence, and dementia or mental decline. It is difficult to diagnose because the symptoms are common to several other diseases. The usual treatment is installation of a shunt to drain excess CSF into another part of the body. This treatment can reverse the symptoms and restore normal functioning, or it may do so partially, or it may not succeed (see below).

NPH is caused by an increase in intracranial pressure (ICP) due to an abnormal accumulation of CSF in the ventricles of the brain, which can cause the ventricles to enlarge (ventriculomegaly). The intracranial pressure gradually falls but still remains slightly elevated, and the CSF pressure reaches a high normal level of 150 to 200 mmH2O. Measurements of ICP, therefore, are not usually elevated. Because of this, patients do not exhibit the classic signs that accompany increased intracranial pressure such as headache, nausea, vomiting, or altered consciousness, although some studies have shown pressure elevations to occur intermittently. However, the enlarged ventricles put increased pressure on the adjacent cortical tissue and cause myriad effects in the patient. The classic symptom triad (gait disturbance, urinary incontinence, and dementia) was first described by Hakim and Adams in 1965.[1] NPH is often misdiagnosed as Parkinson's disease, Alzheimer's disease, or dementia, due to its chronic nature and nonspecific presenting symptoms [see below]. Although the exact mechanism is unknown, normal-pressure hydrocephalus is thought to be a form of communicating hydrocephalus with impaired CSF reabsorption at the arachnoid granulations.

There are two types of normal pressure hydrocephalus: idiopathic and secondary. The secondary type of NPH can be due to a subarachnoid haemorrhage, head trauma, tumour, infection in the central nervous system, or a complication of cranial surgery.[2]

Recent population-based studies have estimated the prevalence of NPH to be about 0.5% in those over 65 years old, with an incidence of about 5.5 patients per 100,000 of people per year.[3][4] This is in accordance with comparable findings stating that although normal pressure hydrocephalus can occur in both men and women of any age, it is found more often in the elderly population, with a peak onset generally in the sixth to seventh decades.[5]

Patients with dementia who are confined to a nursing home and may have undiagnosed NPH can possibly become independent again once treated. So far only one study was able to evaluate the prevalence of NPH, both diagnosed and undiagnosed, among residents of assisted-living facilities, showing a prevalence in 9 to 14% of the residents.[6]

Clinical manifestations[edit]

NPH may exhibit a classic triad of clinical findings (known as the Adams triad or Hakim's triad) of urinary incontinence, gait disturbance, and dementia (commonly referred to as "wet, wobbly and wacky" or "weird walking water").

Diagnosis[edit]

Diagnosis of NPH is usually first led by brain imaging, either CT or MRI, to rule out any mass lesions in the brain. This is then followed by lumbar puncture and evaluation of clinical response to removal of CSF. This can be followed by continuous external lumbar CSF drainage during 3 or 4 days.

Treatment[edit]

NPH may be relieved by surgically implanting a ventriculoperitoneal shunt to drain excess cerebrospinal fluid to the abdomen where it is absorbed. Once the shunt is in place, the ventricles usually diminish in size in 3 to 4 days, regardless of the duration of the hydrocephalus. Even though the ventricular swelling diminishes, only 21% of patients show a marked improvement in symptoms. The most likely patients to show improvement are those that show only gait disturbance, mild or no incontinence, and mild dementia.[11] A more recent study (2004) found better outcomes, concluding that if patients with idiopathic normal pressure hydrocephalus are correctly identified, shunt insertion yielded beneficial outcomes in 86% of patients, in either gait disturbance (81%), improved continence (70%), or both. They also observed that measurements in the diagnostic clinical triad, the cortical sulci size, and periventricular lucencies were related to outcome. However, other factors such as age of the patient, symptom duration, dilation of ventricles, and the degree of presurgical dementia were unrelated to outcome.[12]

References[edit]

  1. ^ Adams, R. D.; Fisher, C. M.; Hakim, S.; Ojemann, R. G.; Sweet, W. H. (15 July 1965). "Symptomatic Occult Hydrocephalus with Normal Cerebrospinal-Fluid Pressure". New England Journal of Medicine 273 (3): 117–126. doi:10.1056/NEJM196507152730301. PMID 14303656. 
  2. ^ National Institute of Neurological Disorders and Stroke. (2011, April 29). NINDS Normal Pressure Hydrocephalus Information Page. Retrieved from http://www.ninds.nih.gov/disorders/normal_pressure_hydrocephalus/normal_pressure_hydrocephalus.htm
  3. ^ Brean, A.; Eide, P. K. (1 July 2008). "Prevalence of probable idiopathic normal pressure hydrocephalus in a Norwegian population". Acta Neurologica Scandinavica 118 (1): 48–53. doi:10.1111/j.1600-0404.2007.00982.x. PMID 18205881. 
  4. ^ Tanaka, Naofumi; Yamaguchi, Satoshi; Ishikawa, Hiroyasu; Ishii, Hiroshi; Meguro, Kenichi (1 January 2009). "Prevalence of Possible Idiopathic Normal-Pressure Hydrocephalus in Japan: The Osaki-Tajiri Project". Neuroepidemiology 32 (3): 171–175. doi:10.1159/000186501. PMID 19096225. 
  5. ^ a b c d Younger, D.S. (2005). Adult Normal Pressure Hydrocephalus. In Younger, D.S. (Ed.), Motor Disorders (2nd edition) (pp. 581-584). Philadelphia, PA: Lippincott Williams & Wilkins.
  6. ^ Marmarou, Anthony; Young, Harold F.; Aygok, Gunes A. (1 April 2007). "Estimated incidence of normal-pressure hydrocephalus and shunt outcome in patients residing in assisted-living and extended-care facilities". Neurosurgical FOCUS 22 (4): 1–8. doi:10.3171/foc.2007.22.4.2. PMID 17613187. 
  7. ^ Krauss, J.K., Faist, M., Schubert, M., Borremans, J.J., Lucking, C.H., & Berger, W. (2001). Evaluation of Gait in Normal Pressure Hydrocephalus Before and After Shunting. In R’uzicka, E., Hallett, M., & Jankovic, J. (Eds.), Gait Disorders (pp.301-309). Philadelphia, PA: Lippincott Williams & Wilkins.
  8. ^ a b Ropper, A.H. & Samuels, M.A. (2009). Adams and Victor’s Principles of Neurology (9th edition). New York, NY: McGraw-Hill Medical.
  9. ^ Tarnaris, Andrew; Toma, Ahmed K; Kitchen, Neil D; Watkins, Laurence D (1 December 2009). "Ongoing search for diagnostic biomarkers in idiopathic normal pressure hydrocephalus". Biomarkers in Medicine 3 (6): 787–805. doi:10.2217/bmm.09.37. PMID 20477715. 
  10. ^ Marmarou, A; Bergsneider, M; Klinge, P; Relkin, N; Black, PM (September 2005). "The value of supplemental prognostic tests for the preoperative assessment of idiopathic normal-pressure hydrocephalus.". Neurosurgery 57 (3 Suppl): S17–28; discussion ii–v. PMID 16160426. 
  11. ^ Vanneste, J; Augustijn, P; Dirven, C; Tan, WF; Goedhart, ZD (January 1992). "Shunting normal-pressure hydrocephalus: do the benefits outweigh the risks? A multicenter study and literature review.". Neurology 42 (1): 54–9. ISSN 0028-3878. PMID 1734324. 
  12. ^ Poca, Maria A.; Mataró, Maria; Matarín, Maria Del Mar; Arikan, Fuat; Junqué, Carmen; Sahuquillo, Juan (1 May 2004). "Is the placement of shunts in patients with idiopathic normal pressure hydrocephalus worth the risk? Results of a study based on continuous monitoring of intracranial pressure". Journal of Neurosurgery 100 (5): 855–866. doi:10.3171/jns.2004.100.5.0855. PMID 15137605. 

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